Related Experiment Video
Updated: Jul 11, 2026

Three-dimensional Optical-resolution Photoacoustic Microscopy
Published on: May 3, 2011
Modeling the propagation of nonlinear three-dimensional acoustic beams in inhomogeneous media
1Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA.
Abstract:
A three-dimensional model of the forward propagation of nonlinear sound beams in inhomogeneous media, a generalized Khokhlov-Zabolotskaya-Kuznetsov equation, is described. The Texas time-domain code (which accounts for paraxial diffraction, nonlinearity, thermoviscous absorption, and absorption and dispersion associated with multiple relaxation processes) was extended to solve for the propagation of nonlinear beams for the case where all medium properties vary in space. The code was validated with measurements of the nonlinear acoustic field generated by a phased array transducer operating at 2.5 MHz in water. A nonuniform layer of gel was employed to create an inhomogeneous medium. There was good agreement between the code and measurements in capturing the shift in the pressure distribution of both the fundamental and second harmonic due to the gel layer. The results indicate that the numerical tool described here is appropriate for propagation of nonlinear sound beams through weakly inhomogeneous media.
Related Concept Videos
Propagation of Waves
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Standing Waves in a Cavity
Sound Waves
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
Sound Waves: Interference
Sound as Pressure Waves
The pressure fluctuation depends on the difference in displacements between the successive points in the...
Beams with Symmetric Loadings
The M/EI...

